Buy Now button with Variations

wp-e-commerce.js
    when updating on change in selected variance, update the
corresponding Buy Now button

display.functions.php -
    include a hidden field in the Buy Now form to pass the variation
value(s) to the Add_to_cart
Escape the things

We need to escape the "disabled" attribute. And apparently the Paypal
string has never used the right i18n function
Use Disabled function, clean up code

Cleaner code
Change $ to jQuery for consistency

Since all other jQuery selectors using the jQuery (rather than $
shortcut), the two references to self have modified
Reduce the calls to wpsc_product_has_variations

minor whitespace corrections
Include disabled() in the input string directly

rather than via sprintf
Reapply BuyNow changes to latest Master
Sanitized for your protection

absint on the incoming product_id, add filter for buynow form classes
and sanitize_html_class on the resulting classes
Clean on aisle 2 - printf

Extend with specific argument and force interger for array index
Little light housekeeping for whitespace
Pass disabled as argument to printf

Light housekeeping on the whitespace, insert argument numbering
Merge pull request #425 from 1bigidea/BuyNow-Rebased

BuyNow Buttons with Variations (rebased)